1. Field of the Invention
The present invention relates to an image display device and a light source device for providing light to display images. More particularly, the present invention relates to a planar light source device, a method of driving the planar light source device and a display apparatus having the planar light source device.
2. Description of the Related Art
Liquid crystal display (LCD) apparatuses display images using liquid crystal. When electric fields are applied to the liquid crystal, an arrangement of liquid crystal molecules is changed to adjust optical transmittance of the liquid crystal to display images. An LCD apparatus generally includes a liquid crystal control module that controls the arrangement of the liquid crystal molecules and a light-providing module that provides the liquid crystal control module with light.
The liquid crystal control module includes a first substrate and a second substrate, a first electrode and a second electrode disposed at the first and second substrates, respectively, and a liquid crystal layer interposed between the first and second substrates. The light-providing module includes a light source that generates light and an optical member that enhances optical characteristics of the light.
Quality of images displayed by the liquid crystal control module is influenced by quality of light generated by the light-providing module. A conventional LCD apparatus employs a light emitting diode (LED) that emits point-light or a cold cathode fluorescent lamp (CCFL) that emits linear light. The LED and the CCFL have a low uniformity of luminance. Therefore, the conventional LCD apparatus employs the optical member such as a diffusion sheet, a prism sheet, etc., in order to enhance the uniformity of luminance.
Recently, there has been a desire to increase screen size of the LCD apparatus. To accommodate the desire to increase screen size, generally, the number of light sources used increases. Increasing the number of light sources tends to increase the size and weight of the LCD apparatus. To reduce the number of light sources and thereby minimize size and weight of the LCD apparatus, a planar light source device has been developed.
The planar light source device has a rectangular-shape. The planar light source device includes discharge spaces spaced apart from each other. Invisible light is generated by a working gas in the discharge spaces, and the invisible light is transformed into a visible light by a fluorescent material coated on an inner surface of the planar light source device.
The planar light source device may also have non-uniform luminance depending on an arrangement and/or configuration of the discharge spaces. When luminance of each discharge space is not uniform, the quality of images displayed by the LCD apparatus is deteriorated. Thus, there has been research to improve the uniformity of the luminance of each discharge space.